Health systems, particularly in poorer countries, need to adapt to meet the chronic care needs of older people as the shift to ageing populations gathers pace in low- and middle-income countries, the World Health Organisation (WHO) said on Wednesday.

In a briefing paper to mark World Health Day on Saturday, the WHO points out that developing countries will have less time than wealthy nations to adapt to the challenges of an ageing population – generally defined as people over 60.

While it took more than 100 years for the share of France's population aged 65 or older to increase from 7% to 14%, countries such as Brazil, China and Thailand will experience the same demographic shift in just over 20 years. "This gives them much less time to put in place the infrastructure to address the needs of this older population," said the WHO.

By 2050, 80% of older people will live in low- and middle-income countries. The trend is also evident for the oldest age groups. In the middle of the last century there were just 14 million people aged 80 or older. By 2050, there will be 100 million living in China and 400 million in this age group worldwide.

The main health challenges for older people are non-communicable diseases such as heart disease, stroke, visual impairment, hearing loss and dementia, but current health systems in poorer countries are not designed to meet such chronic care needs.

While heart disease and stroke are the biggest causes of years of life lost, and high blood pressure is a key treatable risk factor for these diseases, only between 4% and 14% of older people in a recent large study in low- and middle-income countries, by the WHO, were receiving effective anti-hypertensive treatment.

Dementia is set to become a major problem for poor countries as well. The World Alzheimer report 2011, from Alzheimer's Disease International, estimated that by 2050 the number of people living with dementia would rise from 36 million to 115 million. The proportion living in low- and middle-income countries would rise from 58% to 71%.

In a letter to the Lancet (pdf), Dr Peter Lloyd-Sherlock, from the school of international development, University of East Anglia, and others say substantial improvements in health can be achieved with relatively cheap and simple interventions, such as the effective management of hypertension, diabetes and high cholesterol, and the promotion of healthy lifestyles, in particular regular physical activity.

"Yet in most countries these interventions are not available to large sections of adult populations. The failure of national governments and international agencies to prioritise these cheap and effective treatments represents a missed opportunity to reduce mortality, illness and disability on an unprecedented scale," they say. "Although the non-communicable disease (NCD) agenda has gathered some momentum in recent years, international health spending in low-income and middle-income countries remains heavily focused on infectious diseases and mother and child health."

They also argue that increased human longevity "should be a cause for celebration" and provide opportunities to rethink health policy for the benefit of all – old and young.

The WHO points out the importance of being physically active, eating a healthy diet, avoiding the harmful use of alcohol and not smoking in early life to stave off problems later, and it urges countries to adopt preventive strategies, such as taxes on tobacco and alcohol, smoke-free workplaces and public places, reduced salt intake in food and increasing public awareness on diet and physical activity.

Ebenezer Adjetey-Sorsey, executive director of the NGO HelpAge in Ghana, said it was pushing for a smoking ban in public places, but faced strong opposition from tobacco companies and the government, which receives income from tobacco taxes.

More broadly, Adjetey-Sorsey said Ghana's growing ageing population posed problems for the country's healthcare system. "The country is ageing very fast and it's becoming a challenge," he said. "The 2010 census showed that 7% of the population is over 50, and we expect that figure to get higher."

Adjetey-Sorsey cited the high costs of Ghana's health insurance system and the lack of community care for the elderly. "We have community health nurses who basically care for children but they should be trained to provide information for old people as well, as it is expensive to send older people to hospital," he said.

A delegation of older campaigners is scheduled to meet Ghana's health minister on Thursday to lobby for changes in the national health insurance scheme (NHIS), which covers only 5.4% of older people – 70 and above.

The delegates will call for the age of exemption from payment of the minimum premium into NHIS to be reduced from 70 to 60 – the definition of an older person in the national ageing policy approved by the cabinet in 2010.

They will also ask that coverage of diseases and drugs should be made more relevant to the healthcare needs of older people. Currently glasses, hearing aids, orthopaedic aids, dentures and treatment of chronic renal failure are not covered.